non breaking signbytes (#5008)

* test-vectors for backwards compatibility:

 - copy & paste test-vectors from v0.33.5 to ensure
 backwards compatibility for vote's SignBytes

* WIP: everything besides time seems to match :-/

* almost

* Found the culprit: field nums weren't consecutive ints ...

* fix order of partset header too

* this last votes-related test can easily be fixed

* some minor changes and fix last failing test

* move proto types back to stdtime, fix various linting

* use libs/protoio

* remvoe commented code

* add comments

* fix tests

* uncomment testscases

* dont ignore error panic

* fix signable test

* fix happy path testing

* fix comment

Co-authored-by: Marko Baricevic <marbar3778@yahoo.com>

scripts/protocgen.sh

@@ -6,6 +6,6 @@ proto_dirs=$(find . -path ./third_party -prune -o -name '*.proto' -print0 | xarg
 for dir in $proto_dirs; do
   protoc \
   -I. \
-  --gogofaster_out=Mgoogle/protobuf/timestamp.proto=github.com/golang/protobuf/ptypes/timestamp,Mgoogle/protobuf/duration.proto=github.com/golang/protobuf/ptypes/duration,plugins=grpc,paths=source_relative:. \
+  --gogofaster_out=Mgoogle/protobuf/timestamp.proto=github.com/gogo/protobuf/types,Mgoogle/protobuf/duration.proto=github.com/golang/protobuf/ptypes/duration,plugins=grpc,paths=source_relative:. \
   $(find "${dir}" -maxdepth 1 -name '*.proto')
 done